1. Field of the Invention
The present invention relates to frame assemblies that are used to support and stretch silk screens for use in a silk screen printing process.
2. Description of the Prior Art
In the many years since their invention, silk screen printing techniques have been used to print images on a wide variety of objects. Today, silk screen printing is the printing method of choice for printing on fabric such as tee shirts, sweat shirts, jackets, hats and the like.
In the silk screening process, a negative of an image is etched into a coated piece of silk screen. The etched silk screen is then placed upon the surface to be printed. Ink is then pressed through the silk screen. The ink passes through the silk screen in the places where the coating has been etched. The result is a positive rendition of the etched negative being reproduced in ink on the surface that was placed against the silk screen.
Prior to a silk screen being placed against a piece of fabric, the silk screen must be suspended in a frame so that the silk screen remains in a fixed position. Once in the frame, the silk screen must also be stretched to remove any slack in the screen that could wrinkle when the ink is pressed through the screen. Not only must a silk screen be tensioned, it must be evenly tensioned in all directions. If a silk screen is not evenly tensioned the image etched on the silk screen will be distorted and consequently the image reproduced from the silk screen will also be distorted.
Over the years many different types of silk screen frames have been produced. A popular type of silk screen frame uses a rectangular frame where a roller is positioned along each side of the frame. The side edges of a rectangular silk screen are connected to the rollers and the rollers are rotated to apply an even tension to the silk screen. Such prior art silk screen frames are exemplified by U.S. Pat. No. 5,937,751 to Newman, entitled, Retensionable Screen Frame And Stretchers; U.S. Pat. No. 5,802,971 to Hamu, entitled Screen Printing Frame Assembly With Screen Anchors; and U.S. Pat. No. 3,601,912 to Dubbs, entitled Woven Screen Stretching Frame.
A problem associated with screen frames having rollers is that it is very difficult to position a silk screen in the same location on the frame after the silk screen has been removed. As such, there are small variations that occur in the image being printed each time the same silk screen is tensioned in such a frame.
In an attempt to make the accurate loading and unloading of silk screens a more repeatable process, frames have been developed that do not use rollers. In such prior art frames, an adjustable slide mechanism is constructed into each frame element. The slide mechanisms typically can move about one inch within the confines of the frame. This enables each edge of the silk screen to be adjusted within the one inch range. Since the silk screen is mechanically attached to the various slides, the exact point of attachment between the silk screen and the frame can be more precisely controlled. Since the placement of the silk screen on the frame can be better controlled, the accuracy of the placement is increased. Such prior art frame assemblies are exemplified by U.S. Pat. No. 3,385,165 to Hughes, entitled Adjustable Stretch Frame For Biaxially Stressing Sheet Material.
A problem with all of the silk screen frames previously described is that the size of the actual frame is fixed. Silk screens come in a variety of different shapes and sizes. In the past, if a particular silk screen was too large or too small for a frame, that frame had to be replaced with one that was an appropriate size.
A need therefore exists for an improved silk screen frame that has a modular construction that allows the frame to be widely adjusted in size. The improved frame also requires the ability to accurately place silk screens within the frame, time after time. These needs are met by the present invention as is described and claimed below.
The present invention is a frame assembly for use in supporting a silk screen. The assembly uses four corner brackets in forming the frame. The corner brackets each contain two perpendicular arms. The corner brackets engage four framing elements, which make up the sides of the completed frame. Each of the framing elements has two ends, wherein each end of a framing element receives one of the corner bracket arms. As such, each of the four corner brackets engages two of the framing elements and orients those elements at a perpendicular. The use of four framing elements joined by four corner brackets therefore results in a rectangular or square frame.
An adjustment mechanism is disposed between each end of the framing elements and each of the corner brackets. The adjustment mechanism adjusts how deep an arm from a corner bracket is received within an end of a framing element. By utilizing the adjustment mechanism, the effective length of each of the sides of the frame can be selectively adjusted. Accordingly, a silk screen being mounted to the frame can be pulled taut in a highly accurate and repeatable manner.